There are some problems associated with being named “Michael Hall” and going by “Mike,” to be sure:

People who ought to know better forget that “Mike” is short for “Michael” and use it for official stuff where they shouldn’t. That can cause trouble with banks and the like, where the occasionally rigid functionary doesn’t care what “Mike” is short for or “Michael” is long for, because they aren’t the same and it’s not what’s on the check, license, etc.

It’s tougher to weed out a certain sort of person who’s, well, presumptuous. If I tell you “Michael” and you insist on “Mike,” you sort of lose half a point. This is my least favorite issue of all, but I’ve been through periods where it mattered.

“No way! Why should I change? He’s the one who sucks.”

So 3 and 4 are stupid, but one and two are pesky.

On the other hand, when I think back to when I started having some sort of preference, I don’t think very highly of where the preference came from.